Boring tool holder



April 4 w. 1.. GROENE 2,278,988

BORING TOOL HOLDER Filed July 24. 1940 ORINQ BAR FEED INVENTOR.

Patented Apr. 7,

UNITED STATES PATENT OFFICE I carcass k some 'rool. nomnn Willard L. Groene; Cincinnati, Ollie, assignmto The a. K. Le Blond Machine Tool Company, Cincinnati, Ohio, a corporation orDelaware v Application July 24,-1'94 o, Serial No; 347,338

8 Claims. (01. 77-58) long tubes "and gun barrels because of the-necessity of the relatively large amount of overhang required of the boring bar to pass through vthe work which would cause it'to spring out of true position relative to the axis of the lathe, particularly when it was attempted to do heavy cutting. Thus it has been necessary in the past to take relatively light cuts to first get a true and smooth bore so that later a packed bit may be used which is guided in this smooth bore. The inadequacy of this former method lies in the great time consuming slow operations of preparing the initial smooth bore and the great difilculty of getting this bore suiliciently accurate and concentric to carry the usual packed bit.

An object of this invention is to provide a boring tool holder which is floatinglyv-mounted on a boring bar for movement perpendicular to thevaxis of rotation of the lathe and adapted to be fed longitudinally of said axis of the tubular member being bored in the lathe.

Another object of this invention is to provid a tool holder which is pivotally mounted on a boring bar having a cutting tool adapted to engage and machine the inside bore ofa work piece in such a way that the cutting action of the of said work piece at a position substantially 90 circumferentially removed from the point at which the cutting tool is operating on said bore I of said work piece.

Another feature of this invention is the pro- 1 tool holder 4 which is pivotally mounted about v the axis 5 of a suitable pin i which issecurely work against the tool is transmitted to the bore vision of a boring tool on a boring bar fioatingly mounted so that its cutting edge may float in a direction substantially tangent to the surface of the work being bored and to limit this floating movement by engagement of the tool'holder with the bore of said work piece.

A still further object of this invention is to provide a fioatingly mounted boring tool holder which is mounted on a pivot fixed on said boring bar and which has a cutting tool also mount-.

ed in said tool holder adapted to engage the-bore of the work piece to be machined and to provide a work surface engaging portion on said tool holder located at a point circumferentially removedfrom the point. of contact ofsaid cutting tool with the bore of said workpiece and positioned in a plane perpendicular to a plane passing through the pivot and the cutting edge of said tool and lying intermediate thereof.

Further features and advantages of this invention will appear from thedetailed description of the drawing in which:

Figure I is a transverse sectionon the line 1-1 v of Figure II showing the end view of a boring bar, with the unique fioatingly mounted boring tool holder mounted thereon, operating upon the bore of a work piece being rotated'in a lathe 'of 'a character, for example, as set forth in Patent #1363506.

Figure 11 is a longitudinal section on the line II--II of Figure 1, showing the side view of the boring bar. the floating boring tool holder arrangement, and itsrelationship to the bore of 1 the work piece being machined.

' In'the drawing is shown a typical tubular work piece I, which is chucked indrotatedin a lathe I of a character shown, for example, in Patent #1,363,506, so-that it rotates'counterclockwise'as shown in Figure I, about the axis of rotation 2 of the lathe. The work piece I has a mush bore 7 la. which is to be machined down to the bore ill" by longitudinally feeding the boring bar 3 to the right as shown inFigure II. a t

On the end 01' this boring bar I is mounted the fixed in thebore I in the boring bar '8 by an appropriate locking set screw 8. This tool holder 4 is thus held in nice sliding floating engagement with the surface in oi the boring bar and carries a suitable cutting tool 9 fixed in an appropriate slot Ill, in the tool holder by the set screws II and also supported in proper position by the back up screw l2 also mounted in the tool holder I and projecting into the slot l0 against the rear portion l3 of the tool.

The downward thrust on the cutting tool 9 caused by the rotation of the work against its cutting edge H, as indicated by the arrow l5, causes the tool holder t to swing about the pivot 5.- However, this motion is completely absorbed by the work engaging roller [6 suitably journaled on a pin H in the tool holder 6, which engages the bor lb of the work I so that the work acts as an opposite and opposing force, as

shown by the arrow It, to oppose the efiect'of the force indicated by the arrow i5.

Thus the cutting edge ll of the cutting tool 9 is arranged to float in the direction defined by the line II, Figure I, limited by engagement oi the roller II with the bore lb. along the tangential line ll relative to the work borebeing 9, as indicated by the angle it, which is substantially a right angle. And it will also be noted that this plane defined by the line 11-11, passes intermediate the axis 5 and the cutting edge or the tool 9, to aiIect the proper relationship oi the sidewise radial thrust absorbing roller it in relation to the cutting action developed against the tool it by rotation of the work I.

It is important to note that the work surface lb need not be initially smooth or concentric with the axis of rotation 2 of the lathe to affect the proper ultimate finish and accuracy of the bore as machined by the cutting edge ll of the tool. It is to be further noted that in the particular illustration of Figure II, the roller I6 is in contact with the finish machined surface lb. This, however, is not essential to the satisfactory operation of this device and it is equally adapted to having its roller l6 operate in engagement with the rough or eccentric bore la 0! the work piece I.

The reason why it is immaterial whether or not the bore engaged by the roller i8 is concen- ,tric or smooth, lies in the unique arrangement and relative position of the pivot point I, the

' cutting edge It and the m1 0 and the axis l'la of the roller l8. Noting particularly Figure I, it can be seen that any irregularities which would cause the roller II to swing to or from the axis oi rotation 2 oi' the lathe, will have substantially no effect whatever on the relationship of the cutting edge ll of the tool relative to this-axis 2 or the desired finished work surface lb oi the work piece I.

mounted on said tool holder adapted to engage a bore oi a work piece to be bored in said lathe, said axis of pivoting and said cutting edge of said tool being positioned in a plane passing through the axis of rotation of said lathe andthe work piece to be bored, and means on said tool holder for engaging the bore of said work piece at a point substantially 90 circumierentially removed from the point of contact of the cutting edge of said cutting tool with the bore of said work piece.

4. In a lathe, a tool carrier, a tool holder pivotally mounted on said tool carrier, a tool mountedon said tool holder adapted to engage a bore of a work piece to be bored in said lathe, said axis of pivoting and said cutting edge of said tool being positioned in a plane passing through the axis of rotation of said lathe and the work piece to be bored, and means on said tool holder for engaging the bore of said work piece, said work engaging member comprising a roller journaled in said work holder, the axis of rotation of said roller lying in a plane perpendicular to said first mentioned plane and passing through the axis of rotation 01 said lathe and work piece. I

5. In a tool feeding device, a boring bar, a

cutting tool mounted on said boring bar with its cutting edge in engagement with a bore of a work piece to be machined so that its cutting edge has tangential floating movement relative to the surface being machined in said bore, and means for limiting said tangential floating movement of the cutting edge of said tool by engagement with said bore of said work piece.

6. In a lathe, a boring bar movable longitudi-- nally oi the axis of rotation of said lathe through a bore of a work piece rotatably mounted in said lathe, a tool holder floatlngly mounted on the end of said boring bar, a tool in said tool holder;

having its cutting edge adapted to engage the bore of said work piece to be machined, means whereby said floatingly mounted tool holder affects tangential floating movement of the cutting edge of said cutting tool relative to the work bore being machined, .and means whereby said tool holder engages the bore oi. said work piece to limit said tangential floating movement of the Having thus fully set forth and described my said tool holder and the cutting edge of said tool lying in a plane passing through the axis of rotation of said lathe, and means on said tool holder for engaging a work piece .to be by the tool in said toolholder.

' 2. In a lathe, a tool carrier, a tool holder pivotally mounted on said tool carrier, a tool,

mounted on said tool holder adapted to engage a bore of a work piece to be bored in said lathe, said axis of pivoting and said cutting edge of said tool being positioned in a plane passing through the axis of rotation of said lathe and'the work piece to be bored, and means on said tool holder for engaging the borepi said work piece.

3. In a lathe, a tool carrier, a tool holder pivotally mounted on said tool carrier, a tool bored cutting edge of said cutting tool.

'7. In a lathe, a-tool carrier, a tool holder pivotally mounted on said tool carrier, a cutting tool in said tool holder, said axis of pivoting of said tool holder lying to one side and the cutting edge of said tool lying on the other side of the axis of rotation oi said lathe in a plane passing through said axis, and means on said tool holder- 'for engaging a work piece to be machined by the tool in said tool'holder.v

a. In a lathe, a tool carrier, a tool holder pivotally mounted on said tool carrier, a cutting tool in said tool holder, said axis of pivoting of said tool holder lying to one side and the cutting edge or said tool lying on the other side of the axis of rotation of said lathe in a plane passing through said axis, and means onsaid tool holder to contact said work piece at a point lying in a plane passing through said axis and perpendicular to said first mentioned plane to limit the pivotal motion-oi said tool holder.

WILLARD L. GROENE. 

